I have played shakuhachi for about two decades now and in that time worked on meri and dai meri a lot in more advanced pieces.

Meri and dai [great / deep] meri are hard to do well on long flutes. We can break this down into two parts:

1. Actually playing and getting the pitch and volume of both sorts of meri.

2. Getting from a kari [normal head unbowed note] to meri, or meri to kari note.

Let’s take each of these in turn.

1. To make a good meri and dai [great or deep] meri it's essential to:
a) reduce air pressure. b) make embouchure more relaxed. c) push jaw forward.

a) Is obvious - often this is made easier as the meri note is often at the end of a phrase. Think of the breath as ‘sliding’ out of the mouth rather than blowing - think haaaa - not blowing out a lot of birthday cake candles. It may help to drop the corners of the mouth a bit - this will help to relax embouchure and with pouting.

In the piece “Hi Fu Mi” you are hit with a Tsu meri right at the start, and it is nice to be able to make this more than just a small feeble ‘shy’ note!

b) Relax the embouchure by pouting slightly and relaxing tension generally. The hole you blow through should be a flattened oval shape. If you don’t make this hole large enough, either the note will be too sharp or the air stream is so ‘thin’ it misses the blowing edge altogether. The pouting also helps to flatten the note, as the hole is the ‘6th’ hole and as you know by shading any hole on a shakuhachi the pitch will drop or go flat. Both pouting and jaw forward will ‘fill’ or shade the 6th hole more.

In playing meri the usual problem is not flat enough - if you should go too flat this is much easier to fix than not going down far enough in pitch in the first place!

c) If you push the jaw forward you will change the angle of breath stream. So, as you meri down, the breath will go straight down the shakuhachi, hitting the blowing edge on the way. You will have to move your jaw forward in sympathy with ‘head down’ so it will take practice to get the two to work exactly together. If you have too small an air stream you may lose the note at some stage of going down – hence don’t have too fine an air stream. Long slow meri, then up again to kari position is a good way to do this. For beginners I suggest practicing on CHI or OU, then extend this to Tsu meri, and to Tsu dai meri later as you get more adept.

It’s critical to get as close as necessary to the blowing edge in dai meri position. If your embouchure is too tense, or corners of lips pulled back, you won’t be able to go down or flat enough in pitch as there is insufficient ‘shading’ of the top hole. Conversely as you come back up you need to get your face away from the utaguchi, otherwise normal [aka kari] notes will be a bit flat – a very common problem with beginners. They are often quite flat on every note.

After a while, when you get sufficient control at dai meri, you can try a relaxed subtle tightening of embouchure - this will 'tighten' up tone quality of the meri note. It also means that you have some tone color changes to work with and your meri/dai meri notes will have life and not be too insipid. They are not necessarily loud or beautiful flute-like notes – a little roughness or breathiness/burble is part of the timbre but they are very important to play at the correct pitch.

Paradoxically, I have found that when you get all of the above right the flute will work for you, but you have to be meri enough. Too high and the flute won’t work in ‘meri mode’. They are subtle instruments…

It also helps a little if your throat is open a bit, as with a slightly more open embouchure there is some 'coupling' into your chest/lungs/throat, which helps with resonance.

When playing Kan tsu meri, you must observe that you need tighter shading of hole 1 otherwise it’s hard to get tsu meri flat enough. As you need more breath to make this particular [tricky] note to sound, it generally tends to be harder to control in pitch and volume than the Otsu [low] register tsu meri and more so going to dai meri [1.8 pitch D natural – RO pitch]

A useful exercise is to play tsu meri without any shading of hole 1. For this you will need very deep meri - both otsu and kan. If you can get a stable, in tune tsu meri then you are getting there! It’s easy to get a semitone lower than Tsu [in 1.8 pitch F to E natural] but to get it another semitone lower [Eb] to tsu meri is another area all together….

2. Getting from a kari [normal head unbowed note] to meri, or meri to kari note.

For those of us who are crazy [silly?] enough to play long flutes [2.4 or greater] the length of the flutes simply complicates the issue!

We have to do some pretty big head bowing ["Kubi furi san nen…" three years neck waving - literally.]

There’s no magic easy fix, it simply takes lots of practice as here we have to change from a relatively static embouchure - playing kari notes - Re Chi Ri Tsu Ro, etc, to the above meri/dai special embouchure, as well as some calisthenics…..

Many players often move their heads in a diagonal path rather than straight up and down, and this has the advantage of lessening neck problems and also spreading the wear and tear on neck joints. It’s also easier to be more accurate with the bowing angle.

A good exercise is to play RE then change to OU meri, which is the same pitch - this will give you some idea of how much head bowing you will need. It’s also good to play, as it’s relatively easy to get a nice Ou meri and great practice for changing embouchure on the way up and down. Do this in both registers.

Note meri change to get each register in tune. [More meri in kan]

On my 2.85 jinashi it’s possible to get lower than otsu RE pitch on OU meri so watch you don’t go down too far but for practice that's also good.

You can never spend too much time playing around with this area of the shakuhachi. It’s not easy but as you get into it, this is 'where the action is' in Honkyoku.

If you get it right you will know, as your dai meri notes will start to get a more solid, centred sound. If they are very quiet and thin or wheezy or sharp then one or more of the above is not quite right. If you haven’t got any sound start from the beginning…

Watch you don’t squeeze up hole 1 too tight in otsu, in an attempt to get the pitch down - it will only result in a small weak sound. Check with your teacher if the flute is working properly in Tsu meri shade hole 1.

I had a flute which was improved dramatically by having hole 1 opened out a mm or so.

Don’t assume it’s you - get the flute checked by a teacher if you are a beginner to make sure it is the flute and not you.

When meri-ing down follow meri with jaw going out - if you get it right you will get sound until you are in extreme dai meri. It might not be very loud but if you can 'track' the sound down with jaw out [and conversely on the way up] then you are doing well. It will take practice to get the jaw out far enough - at full dai meri the jaw joint may feel a bit stretched
or tight. Keep at it. Try to relax everything else [as much as it is possible playing these things…]

On my 2.85 flute, playing Chi in kari position [normal] position, I can get right down to Tsu pitch. In 1.8 pitch A down to F natural. It’s not a very wonderful note but it’s there.

Finally, if you haven’t got some sort of tuner, get one to check pitch until you get stabilized. Eventually you will be able to hear a semitone accurately and if you are at all musical or play another instrument sing the interval.

Very often the meri notes are played a little flatter than tempered western pitch. If you play western classical music on recorders/flutes etc you may have to rethink [re-tune?] your head to play flatter meris than what you hear in western music.

Final notes:-

Make sure you are not playing too flat to start with this is a common problem with beginners in an effort to get a sound due partly to unformed/beginners embouchure and or too low a breath stream. Weak whistle tone sounds are an indication of a too open embouchure/ low breath speed. Later on you might be able to use this sound.

Practice fading note out to nothing without whistle tones. It is possible - adjust embouchure to increase air stream speed a bit as the volume become smaller and smaller till the sound just stops.

There are three degrees of meri - slight, normal meri then dai meri and as you go down the angle become increasingly shallow. The change of head angle between meri and dai meri is quite small compared to kari position to normal meri, which is quite a large angle.